How to Grow Dill and Herb Fennel: Sowing and Harvest

Dill is a kitchen staple in many parts of the world: chopped over potatoes in Scandinavia and Eastern Europe, in pickles across North America, and stirred into yogurt sauces and pilafs from the Balkans to Iran. Fresh dill is never quite as good from a shop as it is straight from the plant.

It is an easy herb to grow from seed, with two quirks: it dislikes having its roots disturbed, and it quickly runs to flower in hot, dry weather. Once you know that, a few sowings will give you leaves for months and seeds at the end.

Sow it where it will grow

Both the Royal Horticultural Society (RHS) and University of Minnesota Extension advise sowing dill directly where it is to grow, because it does not transplant well. The RHS suggests sowing outdoors from mid-spring to mid-summer once the soil has warmed, and Minnesota Extension says to start after the danger of frost has passed.

Choose a sheltered spot in full sun with fertile, well-drained soil. The RHS notes that dill dislikes cold, waterlogged conditions, and Minnesota Extension recommends shelter from strong wind, as the tall, hollow stems may need staking. If you do start seeds indoors, the RHS suggests one seed per module at 15 °C (59 °F) or warmer, and moving them out about four weeks after sowing, before long taproots form.

Why dill bolts, and how to slow it down

Bolting means a plant flowers early and stops making many leaves. The RHS says dill tends to bolt in hot, dry weather, so water it during dry spells. Regular picking also keeps plants bushy and delays flowering.

The other answer is succession sowing. Instead of one big sowing, sow a short row or a pot every two to three weeks until midsummer, as Minnesota Extension suggests. As one batch starts to flower, the next is ready to pick.

What the evidence says

Dill and herb fennel look alike, with fine, feathery leaves and flat yellow flower heads, but they behave differently. The RHS describes dill as a distant relative of fennel. Dill is a short-lived plant you sow again each year, while herb fennel forms a clump that dies back in autumn and regrows from the base each spring. Fennel can reach 2 m (6 1/2 feet) and, according to the RHS, self-seeds very readily, so cut off seed heads you do not want.

Herb fennel is not the same as Florence fennel, the bulb vegetable. For both herbs, the guidance here is about growing and cooking. Health claims for dill or fennel seed teas are a separate question and are not covered by these gardening sources.

Harvesting leaves, flowers and seeds

The RHS says you can start picking dill leaves about six weeks after sowing. Take a few at a time and always leave at least a third of the plant. Leaves wilt and lose flavor fast, so use them soon after picking. Minnesota Extension says drying keeps the color but loses most of the flavor, so fresh is best.

The small yellow flowers are edible, and for pickles Minnesota Extension suggests using a whole flower head while it is still green and flexible. For seeds, cut the heads as they start to turn brown, hang them upside down inside a paper bag in a warm, airy place, and let the seeds drop. Store fully dry seeds airtight, away from heat and light, for up to a year. Herb fennel is harvested the same way: young leaves from early summer, ripe seed heads in late summer.

Questions people ask

This article is for general information only and is not medical advice. Herbs can interact with medicines and health conditions. Talk to a doctor or pharmacist before trying a herbal remedy, especially if you are pregnant, breastfeeding, giving it to a child, or taking any medication.